Small diameter knitting machines are known for knitting hosiery which knit heels or toes of the fabric in two knitting feeds by reciprocatory knitting. Said knitting feeds are provided with couples of pickers to set the needles out of operation during reciprocatory run. Cam systems of said machines are arranged so that it is possible to perform selection for pearl and jacquard patterns. It is therefore necessary to create a channel between the knitting feeds for passage of the needles and this increases the circumference of the needle cylinder.
Additionally, there are difficulties with the cam arrangement with regard to the necessary angular override of the needle cylinder in reciprocatory run. Because the border needles or the butts of the needle guiding sliders in the dead center of the same revolution come for the second time into the zone of action of the pickers a second undesirable setting of the needles out of operation takes place.
This disadvantage is solved by the device according to Czechoslovak Author's Certificate No. 228,279 corresponding German Pat. No. DEOS 32 40 128 where a lever mechanism is associated with the pickers. The levers of said lever mechanism alternately hold the picker out of action during each revolution after setting the needles out of operation, while at the same time it releases the second picker into operative position. Driving force for the levers of the mechanism is taken from the butts of the guiding jacks or of the needles which increases the stress of the butts.
Nevertheless, this known device has the disadvantages that at higher knitting speeds, the butts of the needle jacks or the needles (according to whether it is a one cylinder or a double cylinder knitting machine) are considerably stressed upon narrowing, as they have to swing out the blocking lever beside displacing the picker. In machines, in which the pickers are arranged more remote from each other, the blocking levers take up a large space.